Stock ECU stim - help me out!
#43
Boost Pope
iTrader: (8)
Join Date: Sep 2005
Location: Chicago. (The less-murder part.)
Posts: 33,052
Total Cats: 6,615
So I can pretty much guarantee that as barometric pressure increases, you are going to see an increase in fuel PW and a decrease in spark timing at all operating conditions, because an increase in barometric pressure will cause an increase in computed load.
Or you could always do a parallel install on the bench.
#45
Thanks reverant for finding out this information.
Hopefully this info leads to better understanding of what the stock ecu does for startsup and other conditions.
Hopefully this info leads to better understanding of what the stock ecu does for startsup and other conditions.
#46
Boost Pope
iTrader: (8)
Join Date: Sep 2005
Location: Chicago. (The less-murder part.)
Posts: 33,052
Total Cats: 6,615
If your multimeter does frequency counting, you can use that instead, and not even have to bother adjusting the scope's timescale.
#47
Any new nuggets of wisdom extracted from the stock ECU?
#48
Elite Member
Thread Starter
iTrader: (10)
Join Date: Jun 2006
Location: Athens, Greece
Posts: 5,979
Total Cats: 356
Yeah, the stock ECU fires the injectors half the times the Megasquirt does, and that fucked up everything that I've measured so far, concerning the injectors. I need to figure out how to get the MS to fire the same number of injections as the stock ECU.
#50
When you said the ECU adjusted idle by altering advance, what ranges are we talking here? Thanks
#52
Elite Member
Thread Starter
iTrader: (10)
Join Date: Jun 2006
Location: Athens, Greece
Posts: 5,979
Total Cats: 356
Btw that was the main reason why I decided to go for a full standalone setup.
#53
altered the baro sensor pressure and seen any results?
#54
#55
Boost Pope
iTrader: (8)
Join Date: Sep 2005
Location: Chicago. (The less-murder part.)
Posts: 33,052
Total Cats: 6,615
Rooting around on my hard drive, I found the following scope trace, which I must have taken on a running car, given how ugly the INJ pulse is:
My notes say that this is the INJ 1/3 wire, but that's about it. What bugs me is the filedate- this picture claims to have been taken in 2008, and I'd have already been running a Megasquirt by that time. Maybe the date got corrupted in a file copy operation...
But yeah, there's clearly only one injector shot per engine cycle here. At moderate to high load, I would think that the MS's two-shots-per-cycle would, in theory at least, produce slightly more even fuel distribution, as each amount of fuel will spend the same length of time "lingering" in the port regardless of which cylinder it is on. At idle, however, it may well be that the stock ECU's method is superior, as one shot of fuel can be more precisely metered than two half-shots.
Alas, this capture was taken at idle, so perhaps the stock ECU switches to two-shots-per-cycle at some higher load condition? Can you test for this?
#59
#60
Elite Member
Thread Starter
iTrader: (10)
Join Date: Jun 2006
Location: Athens, Greece
Posts: 5,979
Total Cats: 356
2002 ECU. Look at the funny injection sequence - semi batch or something?!?!? It is fully batch below 500rpm - but only during the first cranking event. Above 500rpm this is what you get:
It goes like this:
1-2
1-3
4-3
4-2
Oh and y8s...alternator no chargy below 300rpm.
It goes like this:
1-2
1-3
4-3
4-2
Oh and y8s...alternator no chargy below 300rpm.